1. Field of the Invention
The present general inventive concept relates to a switching power amplifier system, and more particularly, to an error correction method and apparatus to enhance the performance of a switching power amplifier by using a digital feedback technology of an audio pulse width modulation signal.
2. Description of the Related Art
A conventional switching power amplifier for audio signals may be classified as class A, class B, class AB and class D. The class D amplifier can reduce amplification efficiency drops occurring in class A, class B, and class AB amplifiers. The class D amplifier uses a method in which an audio signal is converted into a pulse width modulation (PWM) signal and switched. Accordingly, the class D amplifier does not experience a data conversion loss, and if a nonlinear component that occurs in an analog part of a switching circuit is overcome, a 100% amplification efficiency can be achieved. A conventional audio system using the above-mentioned class D amplifier includes a microcomputer to control the entire system, a digital signal processor to process a digital signal, a PWM unit to generate a PWM signal by comparing an audio signal and a carrier signal, and a switching power stage to amplify the voltage and current of the PWM signal.
However, the conventional class D power amplifier has a problem in that the nonlinearity of a power stage and ripple noise of a power supply unit deteriorate the audio performance of a system.
Accordingly, in order to solve the above-mentioned problem, a technology related to the conventional switching power amplifier has been disclosed in U.S. Pat. No. 6,768,779 B1 (PCT/DK98/00133) filed on Apr. 1, 1998, entitled “Pulse referenced control method for enhanced power amplification of a pulse modulated signal”.
Referring to FIG. 1, in the technology related to the conventional switching power amplifier, an error processing unit 110 compares an input reference signal (Vr) with an output signal (V0) from a switching power stage 120 and generates an error signal (Ve).
A correction unit 130 generates a correction signal (Vc) by using the error signal (Ve) generated in the error processing unit 110.
However, in the conventional switching power amplifier, an accurate analog loop filter should be separately designed in order to generate the error signal (Ve) in the error processing unit 110, and thus, complexity and cost of a system increase.
Also, in the conventional switching power amplifier, a correction operation should be performed in an analog domain, but it is very difficult to correct the characteristic of external noise or a nonlinear characteristic due to characteristics of an analog signal.